Divided multiplex channel system



Sept. 15, 1942 D s. HULFISH 2 DIVIDED MULTIPLEX CHANNEL SYSTEM Filed Sept. 23, 1939 3 Sheets-Sheet 1 FIG. 1

INWIQTOR.

? DAVID S. HULFISH ATTORNEY.

p 1942- D. s. HULFISH 2,295,580

D IVIDED MULTIPLEX CHANNEL SYSTEM Filed Sept. 23, 1939 3 Sheets-Sheet 2 FIG.2

- INVENTOR.

DAVID S. HULFISH ATTOR NEY.

Sept. 15, 3.942 s U sH 2,295,589

DIVIDED MULTIPLEX CHANNEL SYSTEM Filed Sept. 25, 1939 3 Sheets-Sheet 3 INVENTOR. DAVID S. HULFISH Patented Sept. 15, 1942 DlVlIDED MULTIPLEX CHANNEL SYSTEM David S. Huifish, Chicago, IlL, assignor t Teletype Corporation, Chicago, 111., a corporation. of

Delaware Application September 23, 1939, Serial No. 296,181

11 Claims.

This invention relates to telegraph signaling systems and more particularly to systems for transmitting a plurality of messages concurrently from an invariable number of transmitters over a single transmission path to a corresponding invariabl number of receivers respectively related to the transmitters.

An object of this invention is the transmission of concurrently stored messages one by one or part by part to several telegraph receivers in rotation.

Another object is the utilization of high percentage of line time by the expedient of associating with the transmission path for major time periods only those transmitters in which messages or parts of messages are stored and are awaiting transmission, and for minor time periods those transmitters in which little or no such material is instantly stored.

A still further object of this invention is to provide apparatus whereby a transmission path when assigned to a plurality of transmitters and associated receivers will be utilized to 'a high percentage of time by transmission in substantially continuous manner from a single transmitter to a single associated receiver whenever all other transmitters assignedto the path are idle, or the path will be shared substantially equally between any two active transmitters when all other transmitters assigned to the path are idle, or will be shared substantially equally by all transmitters operating in rotation when all transmitters assigned to the path are in active condition.

A further object is to effect th described divided transmission over one channel of a synchronous multiplex system, the divisional transmission circuits constituting subchannels within the multiplex channel.

A further object is to attain automatically a phase relation between'and among the receivers and transmitters of' the subchannels after the main distributors' of the multiplex system have been started and synchronized, and before transmission over the subchannels is begun.

A further object is to provide means for restoring subchannels into true phas relation automatically while operating, in case such phasing has been disturbed.

Another object is so to dispose the locations of the divers and sundry parts of apparatus within the structure of the invention that a degree of supervision over the instant conditions of transill mission may be exercised at a substation by users of the transmission facilities provided by the invention.

A further object is to phase a substation start stop transmitter by a phasing signal generated-at a central oflice, utilizing novel circuits.

A further object is to operatea start-stop transmitter and a remotely located associated start-stop receiver completely in synchronism, rather than according to present practice of operating the two start-stop distributors at nonsynchronous rotational speed but electrically in phase for the code signalingcharacter impulses.

To achieve the objects of this invention, means is provided for transmitting over a common path from a plurality of subchannel transmitters line by line or message by message. As a provision for successive operation and for preventing any station from monopolizing the common path, means is provided for limiting the length of time during which any station may occupy the path continuously without offering Opportunity to other transmitters to seize th path should one of the other transmitters be in active condition for transmission.

A feature of tape storage i providedgand to enable users of the service to supervise the condition of transmission it is provided in a modified form of th invention that the storage and supervision may be effected at the originatingsubstation.

Syn-chronism in operation of the transmitting and receiving start-stop mechanism is attained by provision of a new method and novel 'appa ratus for operating a start-stop system, including circuits for starting the transmitter and the receiver simultaneously by a singlestarting signal impulse which passes through the two starting magnets in series or through equivalent relays, as an improvement over prior practice of starting a transmitting distributor and then delaying transmission of a character code signal until the transmitter first has generated 'a starting signal impulse to start a remote receiver. The present invention decreases the baud index figure of the currents in the extension arm as compared with prior structures having a like character-perminute speed.

A more complete understanding of the invention may be had from the following description taken in conjunction with the accompanying drawings wherein,

Fig. 1 illustrates a circuit system for a multiplex ofiice, showing details for transmitting messages into a multiplex channel;

Fig. 2 illustrates a circuit system for a multi-' plex office showing details for receiving messages from a multiplex channel;

Fig. 3 shows circuit details of apparatus for generating signals at the central ofice shown in Fig. 1;

Fig. 4 shows details of retransmission mechanism and of one substation recorder;

Fig. 5 shows circuit details of central office and substation equipment suitable for co-operation with the system shown in Fig. 1 and providing for message storage at the substation; and

Fig. 6 shows details of retransmission mechanism and substation recorder alternative to the similar system shown in Fig. 4.

By combining Figs. 3, 1, 2 and 4, left to right in the order of mention, there is produced a complete circuit of an embodiment of the invention and by combining in similar manner Figs. 5, 1, 2 and 6, there is produced a complete circuit of a modified form of the invention.

Like numerals refer to like parts throughout the several views. Numerals 1 to 6, inclusive, are descriptive as also are letters shown in the drawings, and these are not to be taken as reference numerals. Assemblies and groups of parts are indicated by leading lines having arrow tips.

In general, a transmission path is equipped at the transmitting end with a distributor of any type which connects the transmission path at all times to one of a plurality of transmitters as signed to that path. Transmitters are connected in rotation and in invariable order to the path. At the remote or receiving end of the path a distributor of any type responds to received predetermined control signal code impulses and connects to the path the corresponding recorders in invariable rotational order. A message is recorded at the transmitting end in a perforated tape and is transmitted from the tape. Interruption of transmission may be effected by a code signal in the tape, by control of a taut tape switch or by a time limit device. Limiting the tenure of the common path by any station or transmitter is accomplished by a timing device or equivalent operated by the transmitting means.

More specifically there is illustrated in Figs.

1, 2, 3 and 4 jointly a typical structure embodying the invention in which a multiplex channel is subchanneled to three tape transmitters and to three start-stop recorders. Referring to Figs. 1 and 3, a multiplex transmitting distributor It! has five segments pertaining to one multiplex channel, the segments being connected through five conductors in cable IE to transmitting contacts I2 in five transmitting relays I3 individually numbered I to 5. Windings of relays l3 are connected through five conductors in branching multiple to contacts I4 of three tape transmitters l5, I6, and H.

A subchannel distributor, indicated generally as 20, comprises a continuously driven power shaft 2| and a frictionally driven cam sleeve 22 with ratchet 23 and four cams 24, 25, 25, and 21. Ratchet 23 is controlled by magnet 28 through armature dog 29 to stop the cam sleeve 22 in any one of four stop positions, as determined by the teeth of the ratchet 23, In each of its stop po- I nected contacts 35 or contacts 3! of relays I3 and. then through windings of magnets 38 and 28 to: grounded battery.

A motor 40 drives a snail 4| to propel a snail follower 42 which is pivoted upon the armature of magnet 38 and which will engage and close; the contacts 43. Collector ring 44 of distributor I0 is connected in circuit with the winding; of transmitting relay 45, the armature and contacts of which connect either positive or negative grounded battery to the apex of duplexing relay 45 and thence through line 41 to a remote receiving duplexing relay 48, Fig, 2.

There are shown in Fig. 3 three identical tape storage assemblies, one of which comprises a tape perforator 50 which may be either keyboard controlled or remotely controlled to perforate a tape 5|, a relay 52, a relay 53, and a tape senser deviceincluding magnet 54, armature 55, feeler slides 56, feeler slide contacts I4, and taut tape switch 51.

A circuit extending from ground and back contact of relay 35, Fig. 1, and thence through resistor M5 to branching multiple conductors may be completed through any one of the three camcontrolled contacts 3|, 32, and 33, and from a closed one of said contacts through the winding of one of the relays 53, I20, I24 to grounded battery, the described circuit extending also in a branch conductor through a winding of relay 52 and through a front contact of relay 52 to grounded battery when relay 52 is in operated condition, a condition which is attained initially only by current in a circuit from battery through a wnding of relay 52 and through contacts of a taut tape switch 51 to ground. A circuit from battery through the winding of magnet 54 may be completed to ground either through back contact and armature of relay 53 when unenergized, or through armature and front contact of relay 52 when energized.

Referring to Fig. 2, the multiplex receiving distributor 60 has five segments 6| pertaining to the channel identified with segments I I (Fig. 1) connected through five conductors in a cable 62 to windings of five receiving relays 63 individually numbered I to 5.

Holding circuits for relays 63' extend from ground through winding and contacts of each relay, winding of sixth-impulse-cutout relay 64 and back contact of relay 65 to grounded battery, or alternatively through front contact of relay 65 to grounded battery or through armature 66 and front contact of relay 6'! to grounded battery. Contacts 68 of relays 63 prepare energizing circuits for relays 10, Fig. 4, and the prepared relays I0 may be subsequently energized by current from grounded battery through a winding of each prepared relay I0, contact of relay 95, contact 68, and armature H and contact of relay 6'! when momentarily closed in response to current in a circuit including battery, the winding of relay 6'! and segments I2.

Relays 10, when energized, form each a holding circuit from grounded battery through its winding and contacts 13 and cam controlled contacts II to ground.

A subchannel receiving distributor, indicated generally as 80, is similar to the distributor 20, Fig. 1, and comprises a continuously driven power shaft BI and a frictionally driven cam sleeve 82 with ratchet 83 and four cams 84, 85, 86, and 81. Ratchet 83 is controlled by magnet 83 through armature dog 89 to stop the cam sleeve 82 in any one of four stop positions, as

determined by the ratchet teeth. In each of its stop positions, the cam sleeve 82 will position one of its cams to operate its follower to close one of the three sets of cam controlled contacts 9|, 92, or 93, or to change the contactual relations of the contact set 94.

Each of the cam controlled contact sets 9!, 92 and 93 is connected in a circuit with grounded battery and the winding of a line switching relay 95, 96, or 9?, respectively. Relay contacts 98 and 99, connected in code manner, correspond to similar contacts 36 and 37 in Fig. 1.

Retransmission contacts I90 in storage relay set I are connected to the character signal segments of retransmitting distributors, Fig. 4, of which the distributor I is shown in detail. A further conductor I02 extends from contacts of relays 64 and 61 and thence in branching multiple through contacts in line switching relays 95, 95, and 91 to the starting magnets of the said retransmitting distributors, as shown by magnet I96. The collector ring IIl'I of the distributor I05 is connected to an extension arm line conductor I08 which extends to a substation telegraph receiver which may be of any desired type and which is illustrated as the type of recording receiver fully illustrated and shown in United States Patent No. 1,904,164 issued to S. Morton et al. The magnet I09, Fig. 4, corresponds to the magnet 9 in the Morton et a1. patent and shall be taken to represent an entire receiving equipment according to the Morton patent.

Operation of the system illustrated in Figs. 1, 2, 3, and 4 is as follows:

In Figs. 1 and 3, presume that no perforator 50 has been operated and accordingly all of the tape switches 51 are in operated condition with closed contacts, relays 52 are in energized condition, and magnets 54 are in energized condition, all feeler slides are in withdrawn position, all relays I3 are unenergized, and all contacts I2 are set open or to spacing position. Resultantly, code contacts of the set 36 are all closed. In Figs. 2 and 4, the relays 63 and II! are unenergized and all relay contacts 68 are in open or spacing position.

Initial phasing of the subchannel distributors and 89 will be efiected by code signals sent automatically from distributor 20, presuming that multiplex distributors I0 and 60 have been started and have been phased. In distributor position No. 1, as shown (Figs. 1 and 3), with armature dog 29 in engagement with the No. 1

tooth of ratchet 23 and with contacts 3! closed, the contacts of tape switch 51 of transmitter I5 open and magnet 54 of transmitter I5 energized, brushes of distributor I0 will transmit a blank code signal of five spacing intervals producing or continuing the closed condition of relay contacts 36 and 99. The ensuing sixth-impulse currents from segments 39 and I2 will energize momentarily the relays and 61 which, in the case of relay 35, will generate an impulse in a circuit including ground, front contacts of relay 35, contacts 36, windings of magnets 38 and 28, and grounded battery. In the case of relay 61, an impulse will be generated in a circuit including ground, contact 'II and armature of relay 67, contacts 99, left-hand contacts of set 94, winding of magnet 88, and grounded battery. Armature dogs 29 and 09 are operated simultaneously, cam sleeve 22 rotates all cams 24, 25, 25, 21 into stop position No. 2, while cam sleeve 82 will move from one random position to its next position,

except that if sleeve 82 had been in its No. 4 position with thecontact set 94 in operated position, the last described. circuit will not be closed; and sleeve 82 will remain in No. 4 position;

At the next revolution of the brushes ofdistributor I0 with contacts 32 closed and taut tape in transmitter I6, blank code signal of five spacing impulses will be transmitted, energizing the magnets as before and advancing the cam sleeve 22-. The cam sleeve 82 also will be advanced unless by its progress from a random position it has reacherd its No. 4 position in which case it will remain in its No. 4 position.

In like manner a rotation of the brushes of distributor I0 willcause the cam sleeve 22 to pass from its No. 3 position and into its No. 4 position, and at that time cam sleeve 82 will be in its No. 4 position either reaching No. 4 position simultaneously with sleeve 22, or having waited for sleeve 22' to reach its No. 4 position.

In its No. 4 position, cam sleeve 22 closes contacts 34 to energize and operate relay 2 of set I3, setting up"line feed code signal in contacts I2 o f relays I3. In response to transmission or line feed signal by brushes'of distributor I0, the No. 2 relay of set 63 is energized. Sixth impulses flow in relays 35 and 61. A repeatedsixth-i-mpulse then flows in a circuit, Fig. 1, including ground, front contact of relay 35, contacts 31, winding of magnet 38, winding of magnet 28, and grounded battery, and a further repeated sixthimpulse' flows in a circuit, Fig. 2, including ground, contact and'armatureII of relay 61, contacts 98, right-hand contacts of set 94 in operated condition, winding of magnet 88 and grounded battery. Magnets 23 and 88 are energized simultaneously and cam sleeves 22 and. 82 are stepped at the same time into position N o. 1, thus having been brought into phased relation automatically. Anextension arm equipment, represented :by perforator 50, which may be manually operated or remotely controlled, now has been operatively connected by functions of contacts 3I, Fig. 1, to a multiplex channel and thence to an extension arm represented by conductor I08, Fig. 4, and

recorder I09 by functions of the cam contacts 9I, Fig. 2, and relay 95, energized over an obvi ous circuit.

Presume that while contacts 32, 33, and 34 were operating, perforator had begun operation to provide tape for transmission and that the contacts of taut tape switch 51 accordingly were opened before the present closing of contacts 3|. At cessation of the sixth-impulse through segments 36 and at release of the armature of relay 35, contacts 3| form a circuit including grounded battery, winding of relay 53, contacts 3|, resistor II5, back contacts of relay 35, and ground. Current in this circuit energizes and operates the relay 53 which breaks the energizing circuit of magnet 54 and releases the armature 55 to release the sensing slides 56 which, in turn, operate the transmitter contacts M to energize relays I3 in code manner. Presurning character A to have been sensed in the tape 5|, relays I and 2 of set I3 now will be energized, which is the condition illustrated in Fig. 1.

Brushes of distributor I0 now traverse segments I I to operate relays 45, and 48, and result.- antly relays I, 2, of relay set 63 which close their holding'circuits through winding of relay 64 and contacts of relay 65 to grounded battery, thus preparing operating circuits for relays I and 2 oil set I0. This is the condition illustrated in Fig. 2.

A sixth-impulse of current in relay 35 generated by segments 39 now operates armature and contacts which zclose no circuit, because both contact set 36 and contact set 31 are open, but which open the described circuit of relay 53 permitting de-energization of relay 53 and consequent energization of magnet 54 over an obvious circuit. Upon energization of magnet 54, and operation of armature 55, the sensing slides 56 are withdrawn from the tape and the tape is stepped. At the end of the sixth-impulse, the armature of relay 35 recloses the energizing circuit of relay 53, which, in turn, opens the energized circuit of magnet 54, armature 55 is released, and the sensing slides rise to set upon the code relays I3 the signal code for the next character to be transmitted. Distributor 20 remains unmoved and perforator 50 remains connected to distributor I0.

A sixth-impulse of current in relay 6'! generated by segments 12 simultaneously with the impulse energizes relay 6'! to close contact and armature II to complete the energizing circuit of relays I and 2 of set I0. The energizing circuit includes ground, contact and armature II of relay 67, conductor IIO, [contacts 68, conductors in cable IOI, contacts in operated relay 95, lower windings of relays I and grounded battery, each operated relay I0 forming its own holding circuit from grounded battery through upper winding of relay I0 and cam contact III in distributor I to ground. Operated relay 6! also operates armature 66 to shunt the closed contacts of relay 6'5 and operates another armature to energize relay 65 over an obvious circuit, the armature 66 acting to close its contacts before the relay 65 opens its back contact, thus preserving the continuity of the holding circuits of the relays 63. The armature II2 of relay 6'! also closes a [circuit including ground, front contact I12 and armature II2 of relay 61, armature and front contact of relay 64, conductor I02, sixth-impulse contact of relay 95 now held energized by cam contacts 9|, starting magnet I06 and grounded battery. Magnet I06 is energized, its latching armature is attracted, and distributor I05 starts.

At the end of the sixth-impulse in relay 61, armature II retires from its contact to open the energizing circuit of relays l0. Armature H2 in relay 67 also opens the described sixth-impulse circuit over conductor I02 to de-energize the magnet I96. tact to remove the shunt from contacts of relay 65 and a further armature II3 opens the contacts of the energizing circuit of relay 65 which releases its slow-to-release armature to produce a transit-time break in the holding circuit of relays 63, thus de-energizing all relays 66 and also de-energizing the relay '64.

Although armature 'II in the relay 6'! had connected the ground potential to conductor I I0 and to the contacts of relays No. l of sets 98 and 99, no circuit was completed through these contacts, magnet 68 was not energized and sub-channel distributor 80 remains in its set position, relay 95 remains energized and distributor I05 with extension arm conductor I08 remains connected to the multiplex channel.

Distributor I05 now transmits to line conductor I08 and to recorder I69 a starting impulse followed by five character code impulses under control of contacts I99 of which contacts I and 2 now are closed, and finally a stop impulse is transmitted from grounded battery through resistor H4. During the rotation of distributor I95, an ensuing character code has been transferred to relays I3, Fig. 1, in overlap manner.

Armature 66 retires from its con- Distributor I05 is slightly faster in rotation than distributor 60 so that the brush arm invariably comes to rest in engagement with the armature dog of magnet I06. Character transmission from transmitter I5 to recorder I69 continues as described until at the end of a line, and in response to carriage return code signal, the transmitter I5 operates the relay 4 alone in the set I 3. This results in transmission of carriage return code signal to distributor 60 and in energization of relay 4 alone in set 63. Resultantly, the coded contacts 36 and 99 are closed when the brushes of distributors I0 and 60 engage their respective segments 39 and I2 to generate sixth impulses.

In Fig. 1, relay 35 is energized by the sixth impulse and is operated to close a circuit including contacts 36 and magnets 36 and 2B. Armature of magnet 38 lifts follower 42 from snail M to be returned by its spring. Armature of magnet 28 frees the cam sleeve 22 to rotate, and the cam sleeve rotates for a distance of one tooth, opening the com controlled contacts 3| and closing the cam controlled contacts 32. At the end of the sixth impulse, a circuit from ground through armature and back contact of relay 35 and through resistor II5 will be completed through contacts 32 and magnet I20 instead of through contacts 3i and magnet 53 as before the stepping of the cam sleeve 22. Thus, transmitter I5 has been released and transmitter I6 has been qualified for operation.

In Fig. 2, relay 61 is energized by the sixth impulse, and its four armature members are operated. Armature II connects ground over conductor II 0 and contact of operated relay 4 of set 68, a conductor in cable I6I and a contact .of relay to energize and operate relay 4 in set I0 which forms its holding circuit through its contact 12 and through cam controlled contacts III to ground, thus setting on relay set 10 the code signal transmitted from relay set I3. Armature 66 closes its contacts to shunt the contacts of relay 65. Armature II3 closes its contacts to energize relay 65. Armature II2 closes its contacts to connect ground through armature and contact of relay 64 and through the sixth impulse contact of relay 95 to the starting magnet I06, thus starting the distributor I 05. Armature II also has efiected ground connection over conductor IIO through closed code contacts 99 and through left-hand contacts of set 94 to magnet 88 which attracts its armature 89 and frees the cam sleeve 82, which rotates until stopped by engagement of tooth No. 2 with the armature stop dog 89. Operation of the cam sleeve 82 will open the contacts 9| and close the contacts 92, thus de-energizing the line switching relay 95 and energizing the line switching relay 96. Despite the opening of contacts of relay 95, the distributor I65 continues transmission of the code signal stored in the relay set I0 and just before the distributor I65 stops, the cam control contacts II I are operated momentarily to break the holding circuits of any energized relays in set I6, in this instance relay 4.

By energization of relay I20 and resultant deenergization of transmitter magnet I2I, a code signal sensed in tape II8 of the transmitter I6 is registered upon relays of set I 3. The ensuing rotation of synchronous distributors I0 and 60 will register this code signal on relays of set 63. Then through closed contacts of energized relay 96, the code signal is transferred to the relays of a set corresponding to set I0 associated with the distributor II 9 and with the extension arm line conductor I22 of a recorder, not shown. Ensuing code signals from transmitter I6 will be transmitted through contacts of relays 95 and through distributor H9 until a code signal for carriage return results in closing the coded contact sets 36 and 39 producing a stepping rotation of cam sleeves 22 and 8?. to disconnect transmitter I6 from communication with retransmitter H9 and to connect transmitter I? into communication with retransmitter I2I.

Upon transmission of a carriage return code signal generated in transmitter II, the cam sleeves 22 and 82 step into their position No. 4, thus closing contacts 34 which sets the code signal for line feed on relays I3, as described in the discussion above concerning phasing. The cam sleeves 22 and 82 step into their position No. 1 completing a cycle of transmission with slack tapes.

Should any tape be taut, a blank code signal will be transmitted, as described in the description of phasing above. Thus, the transmitter having no tape supply will be connected to the multiplex channel for a time period of one code signal only. But a transmitter having an available tape supply for transmission will retain connection with the multiplex channel until transmission of a carriage return signal, or until a tape supply has become exhausted.

Should a .tape supply become exhausted, the exhausted tape will become a controlling condition at the beginning of a sixth impulse. When the last available code signal perforation in the tape Fig. 3, has been set upon relays I3, Fig. 1, and has been transmitted over the multiplex channel, the ensuing sixth impulse will energize and operate relay 35 which will interrupt current in relay 53 and permit closure of the energizing circuit of magnet 54. Attraction of armature 55 withdraws slides 56 from the tape 5| and steps the tape, thereby operating the taut tape switch 51 and closing its contact and energizing over an obvious circuit the relay 52 which, by attraction of its armature, closes a shunt upon the closed contacts of relay 53 to control energization of magnet 54. Relay 52 also prepares its holding circuit to be closed by relay 35.

At the end of sixth impulse, the relay 35recloses its back contact, re-energizing the relay 53 and completing the holding circuit of relay 52. Relays of set I3 now are in spacing condition because relay 52 continues the energization of magnet 54 and all slides 56 are held down. Transmission of blank code signal, thus registered on relays I3, results in stepping the cam sleeves 22 and 82 in the manner described in the description of phasing above.

The object of the holding circuit of relay 52 is to prevent mutilation of the transmission of the blank signal registered upon relays I3 as a result of operation of the perforator 50 at random in a transmission cycle.

Should the perforator 50 be controlled by a remote transmitter of a tape printer system, there will be no carriage return code signals in the tape 5|. Accordingly, the snail 4I, follower 42, and contact 43 are provided for advancing the cam sleeves and the magnet 38 is provided for resetting the parts mentioned. After a predetermined lapse of time during which neither contacts 36 nor contacts 31 have been closed, the follower 42 will have been driven by snail 4I into position to close contacts 43, thus connecting resistor I23 in shunt with the winding of relay 53 and rendering that relay marginal. Presume that closure of contacts 43 occurs at an instant when relay 35 is energized and relay '53 is operated, then current will be reduced in relay 53 but will remain suflicient to hold the armature of relay 53 so that no immediate result is effected. Upon energization of relay 35, the relay 53 is deenergized, and upon de-energization of relay 35 the current in the winding of relay 53 will be insufilcient to operate the armature of the relay because of the shunting effect of resistor I23. Hence, the contacts of relay 53 continue to hold the magnet 54 energized, the slides 56 are held down, and blank code signal is registered upon the relays of set I3. Transmission of this code signal followed by a sixth impulse steps the cam sleeves 22 and 82, as described for initial phasing, and the follower 42 is raised for restoration by its spring as a result of momentary energization of magnet 38.

The carriage return code signal, which effects rotation of the cam sleeves 22 and 82, is also retransmitted by a distributor, such as I05, because the code signal is stored in the relay set I0 at the time that the relay 95 is de-energized and the distributor has been started by the impulse over conductor I02. In the case of blank code si nal, however, the code signal is not retransmitted because of the sixth impulse suppression relay 64 which estops the starting impulse in conductor I02. In the case of the line feed code signal for advancing the cam sleeves 22 and 82 out of position No. 4, the code signal is not retransmitted because with the cam sleeves in position No. 4,. all of the relays 95, 96, 91 are de-energized and no extension arm line is connected.

Rephasing of the subchannel distributors 20 and automatically during transmission in case the initial phasing has been disturbed may be provided for by arranging the receiving recorders as IE9 to effect line feed as well as carriagereturn functions in response to receipt of a carriage return code signal, the line feed signal being only by cam contacts 34 for phasing or irregularly for tabulation purposes in'regular transmission.

A modified form of transmitting equipment which may be substituted for the transmitter I5, Fig. 3, is illustrated in Fig. 5. A tape sensing transmitter I3I at a substation at I32 has its transmitting contact tongues I33 connected to the code impulse segments of a transmitting distributor I34, the collector ring I35 of which is connected over line conductor I36 to the feed ring I37 of a central omce receiving distributor I38. Character code segments 1 to 5 of distributor I38 are connected to windings of code signal relays l to 5 of set I40. A starting circuit includes grounded battery I4I, resistor I42, armature I43 and front contact of relay I44, armature I45 and back contact of slow operating relay I46, winding. of starting magnet I41 of distributor I38, resting segment R, brush I48, and feed ring I3! of distributor I 38, line conductor I36, collector ring I35, brush I49, segment R, and starting magnet I50 of substation distributor I34, conductor SI, and contacts I52 of taut tape follower I53 to ground. De-energization of tape sensing magnet I54 permits slides I55 to rise for the purpose of sensing the tape I56, and re-energization of magnet I54 withdraws the slides I55 and steps the tape I56.

A feature of the modified form illustrated in Fig. 5 is to locate the storage tape I56 at-the perforator I57 and keyboard I58 rather than at the central office, thereby keeping the sub.-

holding circuits of all relays of set I40, while armature I6I also is retracted to form a path for discharge of condenser I62, the path thereafter remaining as a shunt around the winding of relay I46. Opening the holding circuit of relays I40 releases all such relays and removes all ground connections from relays I3. At the end of each sixth impulse, the armature of relay .35will be retracted to close a circuit through contacts of relay 35, resistor II5, contacts 3|, winding and contacts of relay I44 and grounded battery I63. Operation of relay I44 closes the starting circuit described above, pending operation of the armature of the slow operating relay I46. Current in this circuit energizes the two starting magnets I41 and I50, attracting their 1 armatures and releasing brushes I48 and I49 for rotation. Upon opening of contacts of armature I6I, current will flow through winding of slow-to-operate relay I46, attracting armature I45 and interrupting the described starting circuit. Brushes I48 and I49 now rotate synchronously in phase and in unison. Brush I64 breaks the obvious energizing circuit of magnet I54 which now releases its armature permitting the rising of slides I55 to sense a code combinational record in tape I56. Contacts I33 thus are adjusted to register a sensed code combination, and the registered code signal is transmitted from battery I65 through contacts I33, distributor I34,

line conductor I36 and distributor I38 to relays I of set I40 which form their holding circuits to armature I60 and which, by their right-hand armatures, set the registered code signal upon the relays of set I3 for transmission by distributor In the event of taut tape in the substation I 32, opening the contacts I52, the relays of set I40 will be released by armature I60 as described to delete the used code signal. The described starting circuit then will be found open at contacts I52, the distributors I34 and I38 will not start and there will be no new registration on the relays of set I40, thus leaving relays of set I 40 and resultantly the relays of set I3 in condition of blank code signal or all spacing. Accordingly, the distributors 20 and 80 are advanced as described for operation of the structure of Fig. 1 in co-operation with the structure of Fig. 3.

Signaling impulses generated by the structure illustrated in Fig. 5, when transmitted through the structures of Fig. 1 and of Fig. 2 are effective for control of the structures illustrated in Fig. 4 as described.

To obtain a lower baud value in a recorder line as I08, a system according to Fig. 6 may be utilized. Fig. 6 is to be combined with Fig. 2, substituting distributor I10 for the distributor I to form a complete circuit diagram of a receiving system.

In Fig. 6, distributor I differs from the distributor I05, Fig. 4, by having fewer segments, and by having starting magnet I1I included in series with the substation selector magnet I19 which corresponds to magnet I09, Fig. 4. The

starting circuit for magnets Ill and I19 extends from ground through contact of relay I80, conductor I13, magnet I1I, segment R, ring I15, line conductor I18, and magnet I19 to grounded battery. The controlling circuit extends from ground through contact I12 and armature II2 of relay 61, Fig. 2, contacts of relay 64, conductor I02, sixth contacts of relay 95, conductor I8I, Fig. 6, and winding of relay I to grounded battery.

In operation of the system of Figs. 2 and 6 jointly, receipt of a code signal is registered on relay set 63 after which a momentary energization of sixth-impulse relay 61 transfers the code signal through contacts '68, Fig. 2, and contacts of relay vto relays I16, Fig. 6, and also supplies a starting impulse over the controlling circuit and starting circuit, traced in detail above, deenergizing the magnets I1I, I19, and startin the central office distributor I10 and the substation distributor, not shown. These two distributors then make one rotation in phase and in synchronism, transferring the registered code signal through contacts I11 to the substation selector magnet I19 in response to which code signal a record is made at the substation. Holding circuits for relays I16 are as described for relays 10.

The invention has been illustrated in connection with specific illustrative systems which are capable of modification without departing from the spirit or scope of the invention, the invention being described only by the scope of the appended claims.

What is claimed is:

1. In a synchronous multiplex system, a multiplex channel, a plurality of transmitters, alike plurality of receivers, means to connect to said multiplex channel said plurality of transmitters one by one in invariable rotational order and said plurality of respectively associated receivers in similar invariable rotational order, means to store in eachsaid transmitter independently of others of said transmitters a variable quantity of code signal indicia, and means to maintain any transmitter in connection with said channel for a period of time which is variable under control of the quantity of said stored signal indicia.

2. In a synchronous multiplex system, a telegraph line, a pair of distributors connected to said line and located at remote points, a pair of sequence switches connected to said distributors respectively, means for driving said sequence switches singly or simultaneously into a phasing position in response to a predeterminedcode signal, and means for driving said sequence switches simultaneously out of said phasing positionin response to another predetermined code signal;

3.'In a synchronous multiplex system, a telegraph line, a pair of distributors connected to said line and located at remote points, a pair of sequence switches connected to said'distributors respectively, means for driving said sequence switches singly or simultaneously into a phasing position in response to a predetermined code signal, means for driving said sequence switches simultaneously out of said phasing position in responseto another predetermined code signal, means in one of said sequence switches when in phasing position for generating said second mentioned code signal, and means for applying the generated second mentioned code signal whereby both of said sequence switches rotate simulta: neously.'

4; In a telegraph system, a substatioma cen tral station, an extension circuit connecting said stations, a synchronous multiplex distributor at said central station connected to said extension circuit, a start-stop telegraph distributor connected to said circuit, a start-stop printer at said substation, a start magnet for said start-stop distributor, a start magnet for said printer, and means controlled by said multiplex distributor for energizing said start magnets simultaneously.

5. In a telegraph system, a synchronous multiplex line, a multiplex distributor in said line, an extension circuit, a start-stop transmitter and a start-stop receiver connected to said extension circuit, a start magnet for said transmitter, a start magnet for said receiver, and means to energize simultaneously the starting magnets of said transmitter and said receiver, respectively, said means controlled by a contact of said multiplex distributor.

6. In a telegraph system, a synchronous multiplex line, a multiplex distributor in said line, an extension circuit, a start-stop transmitter and a start-stop receiver connected to said extension circuit, a contact in said multiplex distributor, and a single start circuit for said extension circuit including the start magnet of said transmitter and the start magnet of said receiver under the control of said contact of said distributor.

'7. In a synchronous multiplex, start-stop extension circuit system, a central station, a substation, a tape senser and a signal distributor at the substation, a receiving start-stop distributor at the central station, a multiplex distributor at the central station electrically connected to the receiving start-stop distributor thereat, a line circuit connecting the distributor at the substation with the receiving distributor at the central station, and means controlled over said line by a contact in the multiplex distributor jointly with a contact in the tape senser to control operation of said tape senser and to regulate the operation of the tape senser according to the operation of the multiplex distributor.

8. In a synchronous multiplex, start-stop extension circuit system, a central station, a substation, a tape senser and a signal distributor at the substation, a taut tape switch associated with said tape senser, a receiving start-stop distributor at the central station, a multiplex distributor at the central station electrically connected to the receiving start-stop distributor thereat, a line circuit connecting the distributor at the substation with the receiving distributor at the central station, and means controlled by a contact in the multiplex distributor and by a contact of said taut tape switch to control operation of said tape senser and to regulate the operation of said tape senser according to the operation of the multiplex distributor when the tape is in a predetermined position.

9. In a telegraph system, a telegraphline, a pair of distributors connected to said line and located at remote points, a sequence switch connected to each of said distributors, means for driving the sequence switches, and means controlled by a predetermined code signal for controlling the operation of said sequence switches to bring them in phase relationship preparatory to telegraphic transmission of intelligence.

10. In a telegraph system, a telegraph line, a pair of distributors connected to said line and located at remote points, a sequence switch connected to each of said distributors, means for driving the sequence switches, means controlled by a predetermined code signal for controlling the operation of said sequence switches to bring them in phase relationship preparatory to telegraphic transmission of intelligence, and means for thereafter operating said sequence switches at variable times during the transmission of intelligence.

11. In a synchronous multiplex system, a telegraph line, a pair of distributors connected to said line and located at remote points, a pair of sequence switches connected to said distributors, respectively, a plurality of transmitters and a plurality of receivers associated with switching connections in said sequence switches, respectively, means for changing said switching connections in said sequence switches at Variable intervals and in variable order, and means controlled by a predetermined code signal for controlling the operation of said sequence switches to bring them into phase relationship preparatory to telegraphic transmission of intelligence.

DAVID S. HULFISH. 

